Human Factors - Egress Analysis for High Hazard Occupancies · Group H • Other SFPE presenters today discussed issues relevant to Group H • This presentation addresses means of

Human Factors - Egress Analysis for High Hazard Occupancies Presented by: Michael J. Klemenz, PE, SFPE

Group H • Other SFPE presenters today discussed

issues relevant to Group H • This presentation addresses means of

egress (MOE) • Prescriptive and engineered methods

Group H Defined • SECTION 307 HIGH-HAZARD GROUP H • 307.1 High-Hazard Group H. High-hazard Group H

occupancy includes, among others, the use of a building or structure, or a portion thereof, that involves the manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities in excess of those allowed in control areas constructed and located as required in Section 414…

Objectives • Means of Egress (MOE) Concepts • Prescriptive Code Requirements • Example • Performance-Based Alternatives • Human Behavior in Fire Emergencies • Q&A

MOE Defined • A continuous and unobstructed path of

vertical and horizontal egress travel from any occupied portion of a building or structure to a public way.

Alternate definition • Engineered building systems that

permit protected travel from the interior of a building [on fire] to the relative safety of the exterior [not on fire] prior to the onset of untenable fire conditions.

Components • A passive fire protection system • Consists of 3 parts:

– Exit Access (“non-protected” path) – Exit (“protected” part) – Exit Discharge (safety)

Generally • Codes normally prescribe at least two

separate & remote egress paths • Exit access travel distance limits apply • Must be maintained for the life of the

building

Two Directions • Keep in mind… • While occupants are exiting the building

during a fire emergency… • Emergency service providers are entering

the building to render aid or mitigate the emergency (fire, EMS, Haz-Mat, etc.)


Codes & Standards • NYS building code Chapter 10 “Means

of Egress” • IBC Chapter 10 • NFPA 101, “Life Safety Code” • OSHA CFR 1910 Subpart E

Occupant Load • The number of persons for which the

means of egress of a building or portion thereof is designed

Gross Floor Area • The floor area within the inside perimeter of the exterior

walls of the building under consideration, exclusive of vent shafts and courts, without deduction for corridors, stairways, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include shafts with no openings or interior courts.

Accessible Moe • A continuous and unobstructed way of

egress travel from any accessible point in a building or facility to a public way.

Exit Access • That portion of a means of egress

system that leads from any occupied portion of a building or structure to an exit.

• Normally no fire resistance rating

Exit • That portion of a means of egress system which is

separated from other interior spaces of a building or structure by fire-resistance-rated construction and opening protectives as required to provide a protected path of egress travel between the exit access and the exit discharge. Exits include exterior exit doors at ground level, exit enclosures, exit passageways, exterior exit stairs, exterior exit ramps and horizontal exits.

Exit Discharge • That portion of a means of egress

system between the termination of an exit and a public way.

Public Way • A street, alley or other parcel of land open to

the outside air leading to a street that has been deeded, dedicated or otherwise permanently appropriated to the public for public use and which has a clear width and height of not less than 10 feet

• It is the final destination for occupants and is assumed to be safe from the emergency in the structure.

Exit Enclosure • An exit component that is separated from

other interior spaces of a building or structure by fire resistance-rated construction and opening protectives, and provides for a protected path of egress travel in a vertical or horizontal direction to the exit discharge or the public way.

Corridor • An enclosed exit access component that

defines and provides a path of egress travel to an exit.

• NOT the same as an exit passageway

Exit Passageway • An exit component that is separated from

all other interior spaces of a building or structure by fire-resistance-rated construction and opening protectives, and provides for a protected path of egress travel in a horizontal direction to the exit discharge or the public way.

Common Path Of Travel • That portion of exit access which the

occupants are required to traverse before two separate and distinct paths of egress travel to two exits are available. Paths that merge are common paths of travel. Common paths of egress travel shall be included within the permitted travel distance.

Exit Access Travel Distance • Exits shall be so located on each story such

that the maximum length of exit access travel measured from the most remote point within a story to the entrance to an exit along the natural and unobstructed path of egress travel, shall not exceed the distances given in Table 1016.1.

Measurement of Travel Distance NFPA 101-7.6*. 7.6.1* The travel distance to an exit shall be measured on the floor

or other walking surface as follows: (1) Along the centerline of the natural path of travel, starting from

the most remote point subject to occupancy (2) Curving around any corners or obstructions, with a 12 in.

clearance therefrom (3) Terminating at (a) Center of the doorway, (b) Other point at

which the exit begins or (c) exit discharge


Example Problem • Single story, 4000 sf. building • Non-separated uses consisting of labs,

offices, storage, process and support spaces

• Construction type per Table 503 • NFPA 13 fire sprinkler system IAW

903.2.4.1

Group H Building • Class 4 Oxidizers- quantity exceeds

Table 307.1.1 for a control area • 307.3 High-Hazard Group H-1. Buildings

and structures containing materials that pose a detonation hazard

EXAMPLE

Refer to Board/Easel

Example 1. Calculate occupant load 2. Evaluate means of egress 3. Make necessary corrections


Occupant Load • Occupant load factors in Table 1004.1.1

– Industrial areas: 100 gross – Accessory storage areas, mechanical equipment

rooms: 300 gross – Business areas: 100 gross

• Where an intended use is not listed in Table 1004.1.1, the code enforcement official shall establish a use based on a listed use that most nearly resembles the intended use.

Also see NFPA 101 Table 7-3.1.2

Occupant Load • Assume occupant load factor of 75 sf.

gross per the AHJ • Occupant load = 4000 sf. ÷ 75/sf.

=53.3 ≈ 54 occupants


Summary of Values for H-1 Feature Value Reference

Number of Exits 2 Table 1019.1*

Exit Access Travel Distance

75’ 1016.1

Common Path of Travel 25’ 1014.3

Dead End Corridor 20’ 1017.3

Corridor Width 44” or per Table 1005.1 1017.2

Exit Remoteness 1/3 max. horizontal 1015.2.1

Corridor FRR 1 hr. w/ 20 min. door Table 1017.1

* Single exit H-1 not permitted by Table 1019.2

Example Occupancy No Sprinklers With Sprinklers

Stairway (in. per occupant)

Other egress components (in. per occupant)

Stairway (in. per occupant)

Other egress components (in. per occupant)

Other than listed below

0.3 0.2 0.2 0.15

Hazardous: H-1, H-2, H-3 & H-4

0.7 0.4 0.3 0.2

Institutional: I-2 NA NA 0.3 0.2

TABLE 1005.1 EGRESS WIDTH PER OCCUPANT SERVED


Ceiling Height & Lighting • 1003.2 Ceiling height. The means of egress

shall have a ceiling height of not less than 7’-6” • 1006.2 Illumination level. MOE illumination

level shall not be < 1 foot-candle (11 lux) at the walking surface level. Power shall be from the premises' electrical supply. Provide E-power (90 minutes) in MOE components.

1006.4 contains detailed photometric and performance requirements


Alternate Methods

• Apply where compliance with prescriptive parameters may not be possible or practical

• Use FP engineering principles and computer modeling to simulate fire development and compare to calculated egress time from a building

Egress Time < Hazardous conditions time

Fire Modeling • ASET (Available Safe Egress Time) is a program

for calculating the temperature and position of the hot smoke layer in a single room with closed doors and windows.

• Used to determine the time to the onset of hazardous conditions for both people and property.

One side of the equation

Fire Modeling • DETACT (DETector ACTuation-Time squared) is

a program for calculating the actuation time of thermal devices

• Used to predict the actuation time of fixed-temperature and rate-of-rise heat detectors and of sprinkler heads subject to a user-specified fire that grows as the square of time.

Fire Modeling • CFAST (Consolidated Model of Fire

Growth and Smoke Transport) is a multi-room fire model that predicts the conditions resulting from a user-specified fire within a structure

Fire Modeling • FDS (Fire Dynamics Simulator) predicts

the transport of heat and smoke from a fire.

• BREAK1 estimates time until glass breaks

• FPEtool is a multi-purpose modeling tool

CFAST Input Parameters • Geometrical data describing the rooms

and connections • Thermophysical properties of the ceiling,

walls, and floors • Fire as a rate of mass loss • Generation rates of the products of

combustion

CFAST Output • Temperature, species concentrations

and thickness of the hot upper layer and the cooler lower layer in each compartment

• Surface temperatures, heat transfer, and mass flow rates

Total Egress Time • Time to Notification • Reaction Time • Pre-evacuation Activity Time • Travel or Movement Time

The other side of the equation

Time to Notification • Fire detection or discovery • Signal processing • Alert signal or message to occupants • Received by occupants? NFPA 72, National

Fire Alarm Code

Reaction Time • Time it takes an occupant to perceive

the alarm or fire cue and then decide what action to take

• Depends on what the occupant perceives

• Immediate danger?

Pre-evacuation Activity Time • Time that elapses while the occupant is

preparing to leave or seek refuge • Safely shut down plant operations? • Make phone calls? • Alert others? • Secure sensitive files & information?

Travel or Movement Time • Time to move to a location of safety • Includes horizontal and vertical travel • 250 ft/min average speed* for

occupants with no impairments? • Significant speed reduction for

occupants with disabilities

Successful MOE Design • Time to the onset of hazardous

conditions for occupants • Total egress time • Egress Time < Hazardous conditions

time


Human Behavior • The way a person reacts to a fire

emergency is dependent on many complex and interrelated factors

• Occupant actions are influenced by the perceived fire threat and observed behavior in others

Evacuation Studies • The earliest documented studies on human

behavior in the United States involved capacity counts of the velocity of pedestrian movement for the New York City design of the Hudson Terminal Building in 1901

• The first edition of the National Fire Protection Association’s Building Exits Code in 1927 (which eventually evolved into NFPA 101®, Life Safety Code®) was developed from evacuation studies conducted during the decade since 1917.

Occupant Interviews • Scientific, post-fire interviews with

people have revealed a great deal of data on occupants’ actions during the fire

• Experiments were performed to observe subjects reactions to fire cues

An Interesting Experiment • College students • While the students were completing a

written questionnaire, the experimenter introduced smoke into the room through a small vent in the wall

• If the students left the room and reported the smoke, the experiment was terminated.

People’s Inhibition of Smoke Cues (Source: B. Latane and J. M. Darley, “Group Inhibition of Bystander Intervention in Emergencies,” Journal of Personality and Social Psychology, Vol. 10, No. 3, 1968, p. 218)

An Interesting Experiment • If the students did not report the presence of

the smoke within 6 minutes from the time they first noticed it, the experiment was considered complete.

• Students alone in the room reported the smoke in 75 percent of the cases. When two passive, noncommittal persons joined each student, only 10 percent of the students reported the smoke.

People’s Inhibition of Smoke Cues (Source: B. Latane and J. M. Darley, “Group Inhibition of Bystander Intervention in Emergencies,” Journal of Personality and Social Psychology, Vol. 10, No. 3, 1968, p. 218)

Consider • Hotel Room, 3AM • Bell ringing in hallway • No visible smoke, odors, etc. • People milling around casually

Explain your general impression and probable state of mind

NOW Consider • Hotel Room, 3AM • Bell ringing in hallway • Smoke visible outside your window • People yelling, crashing, banging • Doorknob feels warm • Sound of fire trucks approaching

Panic Reaction? • Research indicates that people exhibit

panic reaction in a very small (≈<1%) number of instances

• During the decision-making period, people tend to remain calm, ‘analytical’ & cooperative

• Only when directly confronted with direct fire products does panic set in

Questions/Answers

Human Factors - Egress Analysis for High Hazard Occupancies Presented by: Michael J. Klemenz, PE, SFPE

Documents

Human Factors - Egress Analysis for High Hazard Occupancies · Group H • Other SFPE presenters today discussed issues relevant to Group H • This presentation addresses means of